Method and apparatus for compressing a video image

• US 7,006,698 B2
• Filed: 11/25/2003
• Issued: 02/28/2006
• Est. Priority Date: 06/21/1996
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Adiletta, Matthew James, Ho, Samuel William, Wheeler, William Ralph, Rose, Robert Clint, Chow, King-Wai, Sudharsanan, Subramania Iyer
• Primary Examiner(s): Chen, Wenpeng
• Application Number:
  US10/721,947
• Publication Number:
  US 20040131267A1
• Time in Patent Office: 826 Days
• Field of Search: 382/236, 382/232, 382/234, 382/239, 375/240.02, 375/240.01, 375/240.12, 375/240.13, 375/240.16, 375/240.14
• US Class Current: 382/236
• CPC Class Codes: H04N 19/114 Adapting the group of pictures [GOP] structure, e.g. number of B-frames between two anchor frames H04N19/107 takes precedence
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/127 Prioritisation of hardware or computational resources
• CPC Class Codes: H04N 19/132 Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/149 by estimating the code amount by means of a model, e.g. mathematical model or statistical model
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/177 the unit being a group of pictures [GOP]
• CPC Class Codes: H04N 19/31 in the temporal domain
• CPC Class Codes: H04N 19/42 characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation H04N19/635 takes precedence
• CPC Class Codes: H04N 19/423 characterised by memory arrangements H04N19/433 takes precedence
• CPC Class Codes: H04N 19/436 using parallelised computational arrangements
• CPC Class Codes: H04N 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/577 Motion compensation with bidirectional frame interpolation, i.e. using B-pictures
• CPC Class Codes: H04N 19/587 involving temporal sub-sampling or interpolation, e.g. decimation or subsequent interpolation of pictures in a video sequence
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/82 involving filtering within a prediction loop
• CPC Class Codes: H04N 19/87 involving scene cut or scene change detection in combination with video compression
• CPC Class Codes: H04N 19/93 : Run-length coding

Abstract

An apparatus and method for performing two-pass real time video compression is provided. Tactical decisions such as encoding and quantification values are determined in software, whereas functional execution steps are performed in hardware. By appropriately apportioning the tasks between software and hardware, the benefits of each type of processing are exploited, while minimizing both hardware complexity and data transfer requirements. One key concept that allows the compression unit to operate in real time is that the architecture and pipe lining both allow for B frames to be executed out of order. By buffering B frames, two-pass motion estimation techniques can be performed to tailor bit usage to the requirements of the frame, and therefore provide a more appealing output image.

Claims

1. In a video-image processing system, a method for compressing a video image comprising the steps of:

receiving a video signal representing a video image;

calculating a difference value from a current image and a prior image in a compare module;

comparing said difference value to a variable adaptive threshold level,

if said difference value is less than the current value of said variable adaptive threshold level, subtracting said difference value from said current value of said variable adaptive threshold value, thereby producing a new current value of said variable adaptive threshold level, and deleting said video signal,

if said difference value exceeds said variable adaptive threshold value, resetting said variable adaptive threshold to a predetermined beginning threshold value and,

sending said video signal to an encoding and transmitting module.

2. The video-image processing system of claim 1, wherein said step of receiving a video signal representing a video image, further includes a step of measuring a maximum bandwidth capacity of said received video signal, and setting a constant bit rate equal to said maximum bandwidth capacity of the video signal for said video image processing system steps.

3. In a video-image processing system, an apparatus for compressing a video image comprising:

means for receiving a video signal representing a video image, means for calculating a difference value from a current image and a prior image in a compare module,

means for comparing said difference value to a current value of a variable adaptive threshold level,

means for determining if said difference value is less than the current value of said variable adaptive threshold value, and subtracting said difference value from said current value of said variable adaptive threshold value thereby producing a new current value of said variable adaptive threshold value, and deleting said video signal,

means for determining if said difference value exceeds said current value of said variable adaptive threshold value and resetting said variable adaptive threshold to a predetermined beginning threshold value and sending said video signal to an encoding and transmitting module.

4. The video-image processing system of claim 3, wherein said means for receiving a video signal representing a video image, further includes means for measuring a maximum bandwidth capacity of said received video signal, and setting a constant bit rate equal to said maximum bandwidth capacity of the video signal for said video image processing system.